So you think the sun is a serious sphere. Well, it’s a pretty normal star, and not even a large one. Okay. Large enough to shine enough light and distribute enough energy to make our planet inhabitable. Our sun has a diameter of 700,000 kilometres, and fusions hydrogen to helium. It has done so for about 4 billion years now, and will continue to do so for another 3 or 4 billion years, before the lights go out for good in our solar system. The sun is not heavy enough to go supernova, so no good-bye fireworks when the star finally dies. It gets big, eats the two inner planets and Earth will be damn close to the surface of the sun. Then the sun collapses, and that’s it then. A little dwarf in the size of Earth or something will be all that’s left of it, a little sphere remembering the greatness of us having been here.
But you think that’s big? Well, think again.
The largest star known to us is named VY Canis Majoris.
From Wikipedia, the free encyclopedia
Roberta M. Humphreys (2006) estimates the radius of VY CMa is between 1800 and 2100 solar radii. If our sun were replaced with such a star, its surface could extend to the orbit of Saturn. If we take its radius to be that higher figure of 2100 solar radii, it would take more than 2 hours for light to travel around its circumference. If it were possible for a human to walk on the surface of Canis Majoris, at 3 miles an hour for 8 hours a day, it would take him or her 162,000 years to walk the entire circumference (compared with 2 years 11 months to complete the same task on the Earth).
There are two controversial opinions of the property of VY CMa. In one opinion (such as Roberta M. Humphreys’ study[1]), the star is a very large and very luminous red hypergiant. In another opinion (such as Massey, Levesque, & Plez’s study[2]), the star is a normal red supergiant, with a radius around 600 solar radii. In this case, its surface would extend well past the orbit of Mars. This star is likely to undergo a supernova stage by 3200. The distance from Earth to VY CMa is about 1.5 kiloparsecs (or 5,000 light-years).
So this means, in actuality, the star probably is already gone, but the light of the supernova will reach Earth by the year 3200.
This is a comparison between our sun and this star.
So… still think Earth and the sun is big?
Fraser Cain on April 19th, 2008 at 9:37 am says:
I spoke with the Dr. Humphreys, and she said that the largest star possible is 2,600 times the size of the Sun, so VY Canis Majoris is actually pretty close.